Some combinatorial problems in the theory of partial transformation semigroups

• Published in: Algebra and Discrete Mathematics
• Date: 2014
• Main Author: Umar, A.
• Format: Article
• Language: English
• Published: Інститут прикладної математики і механіки НАН України 2014
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/152350
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Some combinatorial problems in the theory of partial transformation semigroups / A. Umar // Algebra and Discrete Mathematics. — 2014. — Vol. 17, № 1. — С. 110–134. — Бібліогр.: 56 назв. — англ.

Let Xn = {1,2,…,n}. On a partial transformation α : Dom α ⊆ Xn → Im α ⊆ Xn of Xn the following parameters are defined: the breadth or width of α is ∣ Dom α ∣, the collapse of α is c(α) = ∣ ∪t∈Imα{tα⁻¹ :∣ tα⁻¹ ∣≥ 2} ∣, fix of α is f(α) = ∣ {x ∈ Xn : xα = x} ∣, the height of α is ∣ Imα ∣, and the rig...